Valentine’s Eve is a fascinating work on a number of levels. Like Opie's earlier novels, it features a rather philosophical heroine, but though some sympathy with republican principles remains, Catherine Shirley is decidedly pious, concluding "Some suppose morality can stand alone without the aid of religion, and even fancy that republican firmness will enable us to bear affliction; but I feel that the only refuge in sorrow and in trial, is the Rock of Ages, and the promises of the gospel." Yet in many ways plot and character are less interesting than the incidentals of this text. For example, the novel foregrounds the role of music in domestic culture and offers such useful insights as the knowledge that modest women did not play the harp in public since it revealed too much of the figure.

Opie's correspondence also indicates that the reception of the novel among her own circle also caused her great distress. She writes to William Hayley that her friend “Lemaistre ... likes neither the plan nor [the] principles–declares Saint-ship in his opinion [the] greatest enemy possible to morals, & is shocked at my having condescended (think of that) to enlist under the banner of Mr. Wilberforce, & Hannah More!!.” However, if Lemaistre found the novel to err on the side of Christian doctrine, how different was the response of Opie's closest friend, Joseph John Gurney: “Joseph took me into his study, & after some preamble, said, he had been [implored] from his intimacy with me, to venture to express to me the pain my late new work had given some of my best & most respectable friends from its impurity, & he said he was desired to tell me, that one gentleman (a notorious profligate by [the] bye) had found it impossible to read parts aloud to ladies–that I alluded to adultery, seduction &c & that Hudson Gurney & his wife ... had written to him, telling him it would be a christian duty in him to admonish me on [the] subject & Hudson said (for he read it to me) that I ... was making the minds of young women impure by communication on such subjects ... I was soon past arguing–for I fell into violent bursts of sorrow ... for indeed I was almost distracted as Lemaistre had been worrying me with long letters against [the] religion of my work, & here, my intimate friends were abusing me for my impurity and immorality!!" (28 February 1816; quoted in Macgregor 64-68). Opie’s frank exploration of the human condition, especially as experienced by women, in the end can satisfy neither the liberal skeptic nor the strict Quaker.